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The K7RA Solar Update


Tad Cook, K7RA, Seattle, reports: As this solar cycle declines, we will occasionally see periods such as this past week, when activity perks up, and it seems that happy days are here again. Enjoy them when you can, while they last. Any recovery is unpredictable and temporary.

Over the July 7-13 reporting week, the average daily sunspot number was52.6 — up by 47.7 points from 4.9 in the previous week. The previous week’s activity was dominated by 5 out of the 7 days with no sunspots. Over the same periods, average daily solar flux rose from 73.1 to 91.6, a healthy advance.

Geomagnetic indices were also active, with planetary A index advancing by 9 points from 6.7 to 15.7. The mid-latitude A index rose from 8.3 to 14.1 over the same 2 weeks.

Predicted solar flux is 94 on July 15; 91 on July 16-18; 86 on July 19; 82 on July 20-21; 80, 77, 75, 73, 74, 73, and 72 on July 22-28;  71, 72, 74, 72, and 77 on July 29-August 2; 83, 87, 92, 94, and 92 on August 3-7; 90 on August 8-13; 85 on August 14; 78 on August 15-16; 76 on August 17, and 77 on August 18-19.

Predicted planetary A index is 14, 8, and 5 on July 15-17; 8 on July 18-19; 5 on July 20-21; 7, 11, 10, and 6 on July 22-25; 4, 6, 7, 9, 8, and 7 on July 26-31; 4 and 5 on August 1-2; 23 on August 3-4; 14, 10, 20, 12, 8, 15, and 10 on August 5-11; 5 on August 12-13; 4 and 14 on August 14-15, and 12 on August 16-17.

Petr Kolman, OK1MGW, provided this geomagnetic activity forecast for July 15-August 10:

  • Quiet on July 16-17, August 1-2
  • Mostly quiet on July 15, 24-26, 31, August 10
  • Quiet to unsettled on July 18, 21-23, 30, August 5-7, 9
  • Quiet to active on July 19-20, 27-29, August 3-4, 8
  • Active to disturbed on August (3-4)
  • Increased solar wind from coronal holes is expected on July 19-21, 27-29, August 2-4, 7-8.

Parentheses indicate lower probability of activity enhancement.

Bill Loftus, WA2VQF, of Denville, New Jersey, was among several who sent this article, commenting, “Good thing I only need 30 more on 80 meters for 5BDXCC.”

Here is a resource from Australia’s Space Weather Services, which displays in detail solar activity over all of the historic cycles, starting in 1754. You might miss this image, which shows all 24 cycles.

On April 13, Ray Bass, W7YKN, of Sparks, Nevada, (he uses the phonetics “You Know Nothing!”) wrote:

“I have a question that so far no one knows the answer to, including some astronomers and professors.

The numbers for the sunspot groups, like 2230, 2231, 2232 and so forth are in numerical order, but where did they start?

Is there a 0001? Did they start, at the beginning of a new 11-year cycle, or when they first started counting sun spots, etc. or did they start with a higher number than 0001?

So, if I started at number 2230 and went backwards to the beginning where would I be (other than lost)?

We had discussions about this a few times on the air in rag chew sessions, and all were interested but no one knew the answer.”

It turns out the renumbering begins after sunspot group 9999, and it starts over at 0. Note that he was not asking about the sunspot number, but the numbering of sunspots. Sunspot number is an indicator of solar activity, but the numbering of sunspots is just a method of identifying individual sunspot groups, and it goes from 0 to 9999. After 10,000 sunspots, the numbers begin all over again. The last time it did this was June 16, 2002.

Go to, and put June 15, 2002, in the archive (Spaceweather Time Machine), and you will see sunspots numbered up to 9998. The next day they start over at 0, and there is also an explanation. Compare the numbers on the sun on these two consecutive days, 14 years ago.

I solved this by using the Spaceweather archive (Time Machine) and kept dialing back the years, and noting the numbers on the solar disc, until I got back to zero. And right there, where it displayed the transition on June 16, 2002, was this explanation:

“SUNSPOT ZERO: This weekend NOAA sunspot region numbers reached 9999 and (like a car's odometer) rolled over to 0000. Sunspot zero spans an area equal to approximately 0.5 planet Earths. It is not particularly large or active — but it will be easy to remember.”

The ARRL Technical Information Service offers more information concerning radio propagation. The ARRL website includes an explanation of the numbers used in this bulletin as well as an archive of past propagation bulletins. The website of Carl Luetzelschwab, K9LA, has more information and tutorials on propagation.

Visit the ARRL website for monthly propagation charts between four US regions and 12 overseas locations and for instructions for starting or ending email distribution of ARRL bulletins.

Sunspot numbers for July 7 through 13 were 25, 55, 63, 46, 62, 63, and 54, with a mean of 52.6. The 10.7 centimeter flux was 83.3, 87.1, 92.2, 94.4, 94.7, 92.4, and 96.8, with a mean of 91.6. Estimated planetary A indices were 23, 23, 14, 10, 11, 21, and 8, with a mean of 15.7. Estimated mid-latitude A indices were 19, 18, 15, 11, 11, 18, and 7 with a mean of 14.1. 



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